🔐 Cracking the Code: Applied Cryptography for Engineers

A comprehensive, month-long cryptography course designed for engineers and cybersecurity enthusiasts. Free and open-source educational resources.

📚 About This Repository

This repository contains all learning materials from an intensive one-month cryptography course taught by me, Pranav Hemanth with Subject Matter Expert Pranavjeet Naidu at PESU I/O. The course covers fundamental to advanced cryptographic concepts with hands-on implementations and CTF challenges.

Our Mission: Make quality cryptography education accessible to everyone, completely free of charge.

🎯 Course Overview

This comprehensive course spans 9 intensive sessions covering:

• Classical Ciphers (Caesar, Vigenère, Substitution)
• Modern Symmetric Encryption (AES, DES)
• Asymmetric Cryptography (RSA)
• Hash Functions and Digital Signatures
• Quantum Computing & Post-Quantum Cryptography (PQC)
• Capture The Flag (CTF) Challenges
• Open Source Intelligence (OSINT) Techniques

📂 Repository Structure

CTC_PESU_I:O/
├── 📄 README.md                          # You are here!
├── 📄 LICENSE                            # MIT License
├── 📋 COURSE_OUTLINE.md                  # Detailed syllabus
├── 📋 QUICK_START.md                     # 5-minute getting started guide
├── 📋 SETUP.md                           # Comprehensive setup instructions
├── 📋 CONTRIBUTING.md                    # Contribution guidelines
├── 📋 CODE_OF_CONDUCT.md                 # Community standards
├── 📋 CHANGELOG.md                       # Version history
├── 📦 requirements.txt                   # Python dependencies
│
├── 📁 Class Materials/
│   ├── CTC Class 1 - Day 0.pdf          # Introduction to Cryptography
│   ├── CTC Class 2 - Day 1.pdf          # Classical Ciphers
│   ├── CTC Class 3 - Day 2.pdf          # Frequency Analysis
│   ├── CTC Class 4 - Day 3.pdf          # Modern Encryption
│   ├── CTC Class 5 - Day 4.pdf          # RSA & Public Key Crypto
│   ├── CTC Class 6 - Day 5.pdf          # Digital Signatures
│   ├── CTC Class 7 - Day 6.pdf          # Hash Functions
│   ├── CTC Class 8 - Day 7.pdf          # Advanced Topics
│   └── CTC Class 9 - Day 8.pdf          # Quantum & PQC
│
├── 📁 Notebooks/
│   ├── H1.ipynb                         # Caesar & Vigenère Cipher Implementations
│   ├── H3.ipynb                         # Cipher Analysis Homework
│   ├── H4.ipynb                         # Advanced Cryptanalysis
│   └── RSALearner.ipynb                 # Interactive RSA Learning Tool
│
├── 📁 CTF Resources/
│   ├── CTF-Crash-Course-Part-1.pdf      # CTF Fundamentals
│   ├── CTF-Crash-Course-Part-2.pdf      # Intermediate Techniques
│   ├── CTF-Crash-Course-Part-3.pdf      # Advanced Strategies
│   └── Capture-The-Flag-A-Cybersecurity-Masterclass.pdf
│
├── 📁 Supplementary Materials/
│   ├── Quantum Computing and PQC.pdf    # Quantum Computing & Post-Quantum Crypto
│   ├── What_is_OSINT.pdf               # OSINT Introduction
│   ├── Question_ Frequency Analysis... # Frequency analysis exercises
│   └── Pranav Hemanth & Pranavjeet Naidu_Cracking the Code...pdf  # Course certificate
│
├── 📁 Scripts/
│   ├── setup.sh                         # Automated setup for macOS/Linux
│   └── setup.ps1                        # Automated setup for Windows
│
└── 📁 .github/
    ├── ISSUE_TEMPLATE/                  # Issue templates
    └── PULL_REQUEST_TEMPLATE.md         # PR template

🚀 Getting Started

Prerequisites

• Python 3.x
• Jupyter Notebook or JupyterLab
• Basic understanding of programming concepts
• Enthusiasm for cryptography! 🔥

Installation

1. Clone this repository

git clone https://github.com/yourusername/CTC_PESU_IO.git
cd CTC_PESU_IO

2. Set up Python environment (recommended)

python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

3. Install required packages

pip install -r requirements.txt

4. Launch Jupyter Notebooks

jupyter notebook

📖 Course Content

Week 1: Foundations

• Day 0: Introduction to Cryptography & Security Principles
• Day 1: Classical Ciphers (Caesar, Substitution)
• Day 2: Frequency Analysis & Cryptanalysis

Week 2: Modern Cryptography

• Day 3: Symmetric Encryption (AES, DES, Block Ciphers)
• Day 4: RSA & Asymmetric Cryptography
• Day 5: Digital Signatures & Certificates

Week 3: Advanced Topics

• Day 6: Hash Functions & Message Authentication
• Day 7: Applied Cryptography in Real Systems
• Day 8: Quantum Computing & Post-Quantum Cryptography

Week 4: Practical Applications

• CTF Challenges & Competitions
• OSINT Techniques
• Real-world Security Analysis

💻 Jupyter Notebooks

Interactive Learning Tools

1. H1.ipynb: Caesar & Vigenère Cipher

   • Implementation from scratch
   • Encryption/Decryption functions
   • Brute force analysis

2. RSALearner.ipynb: RSA Cryptosystem

   • Key generation visualization
   • Prime number selection
   • Encryption/Decryption demonstrations
   • Interactive widgets for learning

3. H3.ipynb & H4.ipynb: Advanced Exercises

   • Cryptanalysis challenges
   • Frequency analysis tools
   • Practical problem-solving

🏆 CTF Resources

This course includes comprehensive Capture The Flag training materials:

• CTF Crash Course (3 Parts): Progressive difficulty levels
• Cybersecurity Masterclass: In-depth competition strategies
• Practical challenges and walkthroughs
• Tools and techniques for competitive cybersecurity

🌟 Key Features

• ✅ 100% Free: All materials open-source and freely available
• 📝 Hands-on: Python implementations of all algorithms
• 🎓 Comprehensive: From basics to quantum-resistant cryptography
• 🔬 Practical: Real-world applications and CTF challenges
• 📊 Interactive: Jupyter notebooks with visualizations
• 🌐 Modern: Includes latest trends (Quantum Computing, PQC)

🤝 Contributing

We welcome contributions from the community! Here's how you can help:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Contribution Ideas

• Add more cipher implementations
• Improve documentation
• Create additional exercises
• Fix bugs or typos
• Add translations

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

👥 Authors & Instructors

• Pranav Hemanth - Subject Matter Expert & Course Instructor
  • GitHub: @pranavhemanth
• Pranavjeet Naidu - Subject Matter Expert & Course Instructor
  • GitHub: @pranavjeetnaidu

🙏 Acknowledgments

• PESU I/O for hosting the course
• All students who participated and provided feedback
• The open-source cryptography community
• Contributors to this repository

📧 Contact & Support

• Issues: Please use the GitHub Issues page
• Discussions: Join our GitHub Discussions
• Email: [your.email@example.com]

🌐 Additional Resources

Recommended Reading

• Introduction to Modern Cryptography by Katz & Lindell
• Cryptography Engineering by Ferguson, Schneier & Kohno
• Applied Cryptography by Bruce Schneier

Online Tools

• CyberChef - The Cyber Swiss Army Knife
• dCode - Cipher tools and solvers
• CrypTool - E-learning platform for cryptography

Practice Platforms

• CryptoHack - Learn cryptography through challenges
• OverTheWire - Wargames for security learning
• picoCTF - Beginner-friendly CTF platform

📊 Course Statistics

• Duration: 1 Month (9 Sessions)
• Format: Hybrid (Theory + Practical)
• Difficulty: Beginner to Advanced
• Languages: Python
• Total Materials: 20+ PDFs, 4 Notebooks

🔮 Future Plans

• Additional programming challenges
• Advanced quantum cryptography module
• Blockchain cryptography section

⭐ Show Your Support

If you found this course helpful, please:

• ⭐ Star this repository
• 🔄 Share with others interested in cryptography
• 🐛 Report any issues you find
• 💡 Suggest improvements or new features

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Made with ❤️ for the cryptography community

"In cryptography, we trust... but verify!" 🔐

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